CASPER, Wyo. (AP) — It got so cold in Wyoming, even the Moscow Ballet couldn't move.

The traveling ballet group famous for performing "The Nutcracker" this time of year couldn't start their buses Thursday morning in Casper.

The temperature in the central Wyoming city plunged to 31 degrees below zero overnight.

Moscow Ballet spokeswoman Sally Michael Keyes says the group's bus and equipment trucks had to be defrosted over several hours.

The delay and worries about driving over snowy passes in Colorado prompted the troupe to cancel a performance Thursday night in Grand Junction, Colorado.

The ballet's home town of Moscow is no stranger to cold and snow, but even Moscow's recent low of 18 degrees wasn't nearly as cold as Casper.

The Moscow Ballet still plans to perform Friday and Saturday in Denver.